I have a product: bottle with liquid,  
 
The liquid of each bottle would can difference through the time (evaporation, extraction, etc.). 
 
 
What could be the best implementation with the app Inventory? Management inventory of quantity of bottles and how much liquid is in each bottle. 
 
 
 
I have tried with this: 
 

• I enabled "lots/serial numbers" in the settings (app inventory) 

• In the product: I checked "Tracking? By Unique Serial Number" 
   

 
 
But when I tried "Operations > Inventory Adjustments" I can't change the quantity of liquid. I only can change the quantity of bottles